* [PATCH 0/2] Add Apple Silicon SMC power driver
@ 2026-01-05 12:56 Michael Reeves via B4 Relay
2026-01-05 12:56 ` [PATCH 1/2] power: supply: Add macsmc-power driver for Apple Silicon Michael Reeves via B4 Relay
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Michael Reeves via B4 Relay @ 2026-01-05 12:56 UTC (permalink / raw)
To: Sebastian Reichel, Sven Peter, Janne Grunau, Neal Gompa, Lee Jones
Cc: linux-kernel, linux-pm, asahi, linux-arm-kernel, Michael Reeves,
Hector Martin
This series adds a power supply driver for the Apple SMC found on
Apple Silicon devices. This allows the kernel to report AC status,
battery charging status, and power metrics, and modify the charging
behaviour.
The first patch adds the driver itself, and the second patch wires it
up to the MFD core.
The driver is based on an original out-of-tree implementation by
Hector Martin. It has been refactored for upstream inclusion,
including support for newer SMC firmwares, devices without batteries,
dynamic property detection and improved state management.
Tested on: Apple M3 (MacBook Air, J613)
Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
---
Michael Reeves (2):
power: supply: Add macsmc-power driver for Apple Silicon
mfd: macsmc: Wire up Apple SMC power driver
MAINTAINERS | 1 +
drivers/mfd/macsmc.c | 1 +
drivers/power/supply/Kconfig | 11 +
drivers/power/supply/Makefile | 1 +
drivers/power/supply/macsmc-power.c | 872 ++++++++++++++++++++++++++++++++++++
5 files changed, 886 insertions(+)
---
base-commit: cc3aa43b44bdb43dfbac0fcb51c56594a11338a8
change-id: 20260105-b4-macsmc-power-d017cc7f53ac
Best regards,
--
Michael Reeves <michael.reeves077@gmail.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 1/2] power: supply: Add macsmc-power driver for Apple Silicon
2026-01-05 12:56 [PATCH 0/2] Add Apple Silicon SMC power driver Michael Reeves via B4 Relay
@ 2026-01-05 12:56 ` Michael Reeves via B4 Relay
2026-01-07 14:35 ` Nick Chan
2026-01-05 12:56 ` [PATCH 2/2] mfd: macsmc: Wire up Apple SMC power driver Michael Reeves via B4 Relay
2026-01-07 7:27 ` [PATCH 0/2] Add Apple Silicon " Neal Gompa
2 siblings, 1 reply; 5+ messages in thread
From: Michael Reeves via B4 Relay @ 2026-01-05 12:56 UTC (permalink / raw)
To: Sebastian Reichel, Sven Peter, Janne Grunau, Neal Gompa, Lee Jones
Cc: linux-kernel, linux-pm, asahi, linux-arm-kernel, Michael Reeves,
Hector Martin
From: Michael Reeves <michael.reeves077@gmail.com>
This driver provides battery and AC status monitoring for Apple Silicon
Macs via the SMC (System Management Controller). It supports
reporting capacity, voltage, current, and charging status.
Co-developed-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
---
MAINTAINERS | 1 +
drivers/power/supply/Kconfig | 11 +
drivers/power/supply/Makefile | 1 +
drivers/power/supply/macsmc-power.c | 872 ++++++++++++++++++++++++++++++++++++
4 files changed, 885 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 0dbf349fc1ed..c18da2295477 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2507,6 +2507,7 @@ F: drivers/nvmem/apple-efuses.c
F: drivers/nvmem/apple-spmi-nvmem.c
F: drivers/pinctrl/pinctrl-apple-gpio.c
F: drivers/power/reset/macsmc-reboot.c
+F: drivers/power/supply/macsmc-power.c
F: drivers/pwm/pwm-apple.c
F: drivers/rtc/rtc-macsmc.c
F: drivers/soc/apple/*
diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index 92f9f7aae92f..3a5b7d9234c2 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -1132,4 +1132,15 @@ config FUEL_GAUGE_MM8013
the state of charge, temperature, cycle count, actual and design
capacity, etc.
+config MACSMC_POWER
+ tristate "Apple SMC Battery and Power Driver"
+ depends on MFD_MACSMC
+ help
+ This driver provides support for the battery and AC adapter on
+ Apple Silicon machines. It exposes battery telemetry (voltage,
+ current, health) and AC adapter status through the standard Linux
+ power supply framework.
+
+ Say Y or M here if you have an Apple Silicon based Mac.
+
endif # POWER_SUPPLY
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 4b79d5abc49a..f5333096f0c3 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -128,3 +128,4 @@ obj-$(CONFIG_CHARGER_SURFACE) += surface_charger.o
obj-$(CONFIG_BATTERY_UG3105) += ug3105_battery.o
obj-$(CONFIG_CHARGER_QCOM_SMB2) += qcom_smbx.o
obj-$(CONFIG_FUEL_GAUGE_MM8013) += mm8013.o
+obj-$(CONFIG_MACSMC_POWER) += macsmc-power.o
diff --git a/drivers/power/supply/macsmc-power.c b/drivers/power/supply/macsmc-power.c
new file mode 100644
index 000000000000..def9b12118c2
--- /dev/null
+++ b/drivers/power/supply/macsmc-power.c
@@ -0,0 +1,872 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SMC Power/Battery Management Driver
+ *
+ * This driver exposes battery telemetry (voltage, current, temperature, health)
+ * and AC adapter status provided by the Apple SMC (System Management Controller)
+ * on Apple Silicon systems.
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/limits.h>
+#include <linux/module.h>
+#include <linux/mfd/macsmc.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/reboot.h>
+#include <linux/workqueue.h>
+
+#define MAX_STRING_LENGTH 256
+
+/*
+ * The SMC reports charge in mAh (Coulombs) but energy in mWh (Joules).
+ * We lack a register for "Nominal Voltage" or "Energy Accumulator".
+ * We use a fixed 3.8V/cell constant to approximate energy stats for userspace,
+ * derived from empirical data across supported MacBook models.
+ */
+#define MACSMC_NOMINAL_CELL_VOLTAGE_MV 3800
+
+/* SMC Key Flags */
+#define CHNC_BATTERY_FULL BIT(0)
+#define CHNC_NO_CHARGER BIT(7)
+#define CHNC_NOCHG_CH0C BIT(14)
+#define CHNC_NOCHG_CH0B_CH0K BIT(15)
+#define CHNC_BATTERY_FULL_2 BIT(18)
+#define CHNC_BMS_BUSY BIT(23)
+#define CHNC_CHLS_LIMIT BIT(24)
+#define CHNC_NOAC_CH0J BIT(53)
+#define CHNC_NOAC_CH0I BIT(54)
+
+#define CH0R_LOWER_FLAGS GENMASK(15, 0)
+#define CH0R_NOAC_CH0I BIT(0)
+#define CH0R_NOAC_DISCONNECTED BIT(4)
+#define CH0R_NOAC_CH0J BIT(5)
+#define CH0R_BMS_BUSY BIT(8)
+#define CH0R_NOAC_CH0K BIT(9)
+#define CH0R_NOAC_CHWA BIT(11)
+
+#define CH0X_CH0C BIT(0)
+#define CH0X_CH0B BIT(1)
+
+#define ACSt_CAN_BOOT_AP BIT(2)
+#define ACSt_CAN_BOOT_IBOOT BIT(1)
+
+#define CHWA_CHLS_FIXED_START_OFFSET 5
+#define CHLS_MIN_END_THRESHOLD 10
+#define CHLS_FORCE_DISCHARGE 0x100
+#define CHWA_FIXED_END_THRESHOLD 80
+#define CHWA_PROP_WRITE_THRESHOLD 95
+
+#define MACSMC_MAX_BATT_PROPS 50
+#define MACSMC_MAX_AC_PROPS 10
+
+struct macsmc_power {
+ struct device *dev;
+ struct apple_smc *smc;
+
+ struct power_supply_desc ac_desc;
+ struct power_supply_desc batt_desc;
+
+ enum power_supply_property *ac_props;
+ enum power_supply_property *batt_props;
+
+ struct power_supply *batt;
+ struct power_supply *ac;
+
+ char model_name[MAX_STRING_LENGTH];
+ char serial_number[MAX_STRING_LENGTH];
+ char mfg_date[MAX_STRING_LENGTH];
+
+ bool has_chwa;
+ bool has_chls;
+ bool has_ch0i;
+ bool has_ch0c;
+ bool has_chte;
+
+ u8 num_cells;
+ int nominal_voltage_mv;
+
+ struct notifier_block nb;
+ struct work_struct critical_work;
+ bool shutdown_started;
+};
+
+static int macsmc_battery_get_status(struct macsmc_power *power)
+{
+ u64 nocharge_flags;
+ u32 nopower_flags;
+ u16 ac_current;
+ int charge_limit = 0;
+ bool limited = false;
+ bool flag;
+ int ret;
+
+ /*
+ * Fallbacks exist for keys that may disappear in future hardware.
+ * CHCE/CHCC/BSFC/CHSC are considered fundamental; absence is an error.
+ */
+
+ /* Check if power input is inhibited (e.g. BMS balancing cycle) */
+ ret = apple_smc_read_u32(power->smc, SMC_KEY(CH0R), &nopower_flags);
+ if (!ret && (nopower_flags & CH0R_LOWER_FLAGS & ~CH0R_BMS_BUSY))
+ return POWER_SUPPLY_STATUS_DISCHARGING;
+
+ /* Check if charger is present */
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(CHCE), &flag);
+ if (ret < 0)
+ return ret;
+ if (!flag)
+ return POWER_SUPPLY_STATUS_DISCHARGING;
+
+ /* Check if AC is charge capable */
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(CHCC), &flag);
+ if (ret < 0)
+ return ret;
+ if (!flag)
+ return POWER_SUPPLY_STATUS_DISCHARGING;
+
+ /* Check if AC input limit is too low */
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-i), &ac_current);
+ if (!ret && ac_current < 100)
+ return POWER_SUPPLY_STATUS_DISCHARGING;
+
+ /* Check if battery is full */
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(BSFC), &flag);
+ if (ret < 0)
+ return ret;
+ if (flag)
+ return POWER_SUPPLY_STATUS_FULL;
+
+ /* Check for user-defined charge limits */
+ if (power->has_chls) {
+ u16 vu16;
+
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16);
+ if (ret == 0 && (vu16 & 0xff) >= CHLS_MIN_END_THRESHOLD)
+ charge_limit = (vu16 & 0xff) - CHWA_CHLS_FIXED_START_OFFSET;
+ } else if (power->has_chwa) {
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag);
+ if (ret == 0 && flag)
+ charge_limit = CHWA_FIXED_END_THRESHOLD - CHWA_CHLS_FIXED_START_OFFSET;
+ }
+
+ if (charge_limit > 0) {
+ u8 buic = 0;
+
+ if (apple_smc_read_u8(power->smc, SMC_KEY(BUIC), &buic) >= 0 &&
+ buic >= charge_limit)
+ limited = true;
+ }
+
+ /* Check charging inhibitors */
+ ret = apple_smc_read_u64(power->smc, SMC_KEY(CHNC), &nocharge_flags);
+ if (!ret) {
+ if (nocharge_flags & CHNC_BATTERY_FULL)
+ return POWER_SUPPLY_STATUS_FULL;
+ /* BMS busy shows up as inhibit, but we treat it as charging */
+ else if (nocharge_flags == CHNC_BMS_BUSY && !limited)
+ return POWER_SUPPLY_STATUS_CHARGING;
+ else if (nocharge_flags)
+ return POWER_SUPPLY_STATUS_NOT_CHARGING;
+ else
+ return POWER_SUPPLY_STATUS_CHARGING;
+ }
+
+ /* Fallback: System charging flag */
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(CHSC), &flag);
+ if (ret < 0)
+ return ret;
+ if (!flag)
+ return POWER_SUPPLY_STATUS_NOT_CHARGING;
+
+ return POWER_SUPPLY_STATUS_CHARGING;
+}
+
+static int macsmc_battery_get_charge_behaviour(struct macsmc_power *power)
+{
+ int ret;
+ u8 val8;
+ u8 chte_buf[4];
+
+ if (power->has_ch0i) {
+ ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0I), &val8);
+ if (ret)
+ return ret;
+ if (val8 & CH0R_NOAC_CH0I)
+ return POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE;
+ }
+
+ if (power->has_chte) {
+ ret = apple_smc_read(power->smc, SMC_KEY(CHTE), chte_buf, 4);
+ if (ret < 0)
+ return ret;
+
+ if (chte_buf[0] == 0x01)
+ return POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
+ } else if (power->has_ch0c) {
+ ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0C), &val8);
+ if (ret)
+ return ret;
+ if (val8 & CH0X_CH0C)
+ return POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
+ }
+
+ return POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO;
+}
+
+static int macsmc_battery_set_charge_behaviour(struct macsmc_power *power, int val)
+{
+ int ret;
+
+ /* First, reset all inhibitors to a known-good 'auto' state */
+ if (power->has_ch0i) {
+ ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 0);
+ if (ret)
+ return ret;
+ }
+
+ if (power->has_chte) {
+ ret = apple_smc_write_u32(power->smc, SMC_KEY(CHTE), 0);
+ if (ret)
+ return ret;
+ } else if (power->has_ch0c) {
+ ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 0);
+ if (ret)
+ return ret;
+ }
+
+ switch (val) {
+ case POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO:
+ return 0;
+
+ case POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE:
+ if (power->has_chte)
+ return apple_smc_write_u32(power->smc, SMC_KEY(CHTE), 1);
+ else if (power->has_ch0c)
+ return apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 1);
+ else
+ return -EOPNOTSUPP;
+ break;
+
+ case POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE:
+ if (!power->has_ch0i)
+ return -EOPNOTSUPP;
+ return apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 1);
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static int macsmc_battery_get_date(const char *s, int *out)
+{
+ if (!isdigit(s[0]) || !isdigit(s[1]))
+ return -EOPNOTSUPP;
+
+ *out = (s[0] - '0') * 10 + s[1] - '0';
+ return 0;
+}
+
+static int macsmc_battery_get_capacity_level(struct macsmc_power *power)
+{
+ bool flag;
+ u32 val;
+ int ret;
+
+ /* Check for emergency shutdown condition */
+ if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val) >= 0 && val)
+ return POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
+
+ /* Check AC status for whether we could boot in this state */
+ if (apple_smc_read_u32(power->smc, SMC_KEY(ACSt), &val) >= 0) {
+ if (!(val & ACSt_CAN_BOOT_IBOOT))
+ return POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
+
+ if (!(val & ACSt_CAN_BOOT_AP))
+ return POWER_SUPPLY_CAPACITY_LEVEL_LOW;
+ }
+
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(BSFC), &flag);
+ if (ret < 0)
+ return POWER_SUPPLY_CAPACITY_LEVEL_UNKNOWN;
+
+ if (flag)
+ return POWER_SUPPLY_CAPACITY_LEVEL_FULL;
+ else
+ return POWER_SUPPLY_CAPACITY_LEVEL_NORMAL;
+}
+
+static int macsmc_battery_get_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ union power_supply_propval *val)
+{
+ struct macsmc_power *power = power_supply_get_drvdata(psy);
+ int ret = 0;
+ u8 vu8;
+ u16 vu16;
+ s16 vs16;
+ s32 vs32;
+ s64 vs64;
+ bool flag;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_STATUS:
+ val->intval = macsmc_battery_get_status(power);
+ ret = val->intval < 0 ? val->intval : 0;
+ break;
+ case POWER_SUPPLY_PROP_PRESENT:
+ val->intval = 1;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+ val->intval = macsmc_battery_get_charge_behaviour(power);
+ ret = val->intval < 0 ? val->intval : 0;
+ break;
+ case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0TE), &vu16);
+ val->intval = vu16 == 0xffff ? 0 : vu16 * 60;
+ break;
+ case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0TF), &vu16);
+ val->intval = vu16 == 0xffff ? 0 : vu16 * 60;
+ break;
+ case POWER_SUPPLY_PROP_CAPACITY:
+ ret = apple_smc_read_u8(power->smc, SMC_KEY(BUIC), &vu8);
+ val->intval = vu8;
+ break;
+ case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
+ val->intval = macsmc_battery_get_capacity_level(power);
+ ret = val->intval < 0 ? val->intval : 0;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CURRENT_NOW:
+ ret = apple_smc_read_s16(power->smc, SMC_KEY(B0AC), &vs16);
+ val->intval = vs16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_POWER_NOW:
+ ret = apple_smc_read_s32(power->smc, SMC_KEY(B0AP), &vs32);
+ val->intval = vs32 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(BITV), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
+ /* Calculate total max design voltage from per-cell nominal voltage */
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(BVVN), &vu16);
+ val->intval = vu16 * 1000 * power->num_cells;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_MIN:
+ /* Lifetime min */
+ ret = apple_smc_read_s16(power->smc, SMC_KEY(BLPM), &vs16);
+ val->intval = vs16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_MAX:
+ /* Lifetime max */
+ ret = apple_smc_read_s16(power->smc, SMC_KEY(BLPX), &vs16);
+ val->intval = vs16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RC), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RI), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RV), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0DC), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_FULL:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0FC), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_NOW:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
+ /* B0RM is Big Endian, likely pass through from TI gas gauge */
+ val->intval = (s16)swab16(vu16) * 1000;
+ break;
+ case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0DC), &vu16);
+ val->intval = vu16 * power->nominal_voltage_mv;
+ break;
+ case POWER_SUPPLY_PROP_ENERGY_FULL:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0FC), &vu16);
+ val->intval = vu16 * power->nominal_voltage_mv;
+ break;
+ case POWER_SUPPLY_PROP_ENERGY_NOW:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
+ /* B0RM is Big Endian, likely pass through from TI gas gauge */
+ val->intval = (s16)swab16(vu16) * power->nominal_voltage_mv;
+ break;
+ case POWER_SUPPLY_PROP_TEMP:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0AT), &vu16);
+ val->intval = vu16 - 2732; /* Kelvin x10 to Celsius x10 */
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_COUNTER:
+ ret = apple_smc_read_s64(power->smc, SMC_KEY(BAAC), &vs64);
+ val->intval = vs64;
+ break;
+ case POWER_SUPPLY_PROP_CYCLE_COUNT:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(B0CT), &vu16);
+ val->intval = vu16;
+ break;
+ case POWER_SUPPLY_PROP_SCOPE:
+ val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
+ break;
+ case POWER_SUPPLY_PROP_HEALTH:
+ flag = false;
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(BBAD), &flag);
+ val->intval = flag ? POWER_SUPPLY_HEALTH_DEAD : POWER_SUPPLY_HEALTH_GOOD;
+ break;
+ case POWER_SUPPLY_PROP_MODEL_NAME:
+ val->strval = power->model_name;
+ break;
+ case POWER_SUPPLY_PROP_SERIAL_NUMBER:
+ val->strval = power->serial_number;
+ break;
+ case POWER_SUPPLY_PROP_MANUFACTURE_YEAR:
+ ret = macsmc_battery_get_date(&power->mfg_date[0], &val->intval);
+ /* The SMC reports the manufacture year as an offset from 1992. */
+ val->intval += 1992;
+ break;
+ case POWER_SUPPLY_PROP_MANUFACTURE_MONTH:
+ ret = macsmc_battery_get_date(&power->mfg_date[2], &val->intval);
+ break;
+ case POWER_SUPPLY_PROP_MANUFACTURE_DAY:
+ ret = macsmc_battery_get_date(&power->mfg_date[4], &val->intval);
+ break;
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
+ if (power->has_chls) {
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16);
+ val->intval = vu16 & 0xff;
+ if (val->intval < CHLS_MIN_END_THRESHOLD || val->intval >= 100)
+ val->intval = 100;
+ } else if (power->has_chwa) {
+ flag = false;
+ ret = apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag);
+ val->intval = flag ? CHWA_FIXED_END_THRESHOLD : 100;
+ } else {
+ return -EINVAL;
+ }
+ if (psp == POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD &&
+ ret >= 0 && val->intval < 100 && val->intval >= CHLS_MIN_END_THRESHOLD)
+ val->intval -= CHWA_CHLS_FIXED_START_OFFSET;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return ret;
+}
+
+static int macsmc_battery_set_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val)
+{
+ struct macsmc_power *power = power_supply_get_drvdata(psy);
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+ return macsmc_battery_set_charge_behaviour(power, val->intval);
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
+ /*
+ * Read-only reflection of end threshold logic.
+ * Allowed to be written to avoid userspace confusion, but ignored.
+ */
+ return 0;
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
+ if (power->has_chls) {
+ u16 kval = 0;
+ /* Configurable logic for future expansion */
+ if (val->intval < CHLS_MIN_END_THRESHOLD)
+ kval = CHLS_FORCE_DISCHARGE | CHLS_MIN_END_THRESHOLD;
+ else if (val->intval < 100)
+ kval = CHLS_FORCE_DISCHARGE | (val->intval & 0xff);
+
+ return apple_smc_write_u16(power->smc, SMC_KEY(CHLS), kval);
+ } else if (power->has_chwa) {
+ return apple_smc_write_flag(power->smc, SMC_KEY(CHWA),
+ val->intval <= CHWA_PROP_WRITE_THRESHOLD);
+ } else {
+ return -EINVAL;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int macsmc_battery_property_is_writeable(struct power_supply *psy,
+ enum power_supply_property psp)
+{
+ struct macsmc_power *power = power_supply_get_drvdata(psy);
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
+ return true;
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
+ return power->has_chwa || power->has_chls;
+ default:
+ return false;
+ }
+}
+
+static const struct power_supply_desc macsmc_battery_desc_template = {
+ .name = "macsmc-battery",
+ .type = POWER_SUPPLY_TYPE_BATTERY,
+ .get_property = macsmc_battery_get_property,
+ .set_property = macsmc_battery_set_property,
+ .property_is_writeable = macsmc_battery_property_is_writeable,
+};
+
+static int macsmc_ac_get_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ union power_supply_propval *val)
+{
+ struct macsmc_power *power = power_supply_get_drvdata(psy);
+ int ret = 0;
+ u16 vu16;
+ u32 vu32;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_ONLINE:
+ ret = apple_smc_read_u32(power->smc, SMC_KEY(CHIS), &vu32);
+ val->intval = !!vu32;
+ break;
+ case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-n), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-i), &vu16);
+ val->intval = vu16 * 1000;
+ break;
+ case POWER_SUPPLY_PROP_INPUT_POWER_LIMIT:
+ ret = apple_smc_read_u32(power->smc, SMC_KEY(ACPW), &vu32);
+ val->intval = vu32 * 1000;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return ret;
+}
+
+static const struct power_supply_desc macsmc_ac_desc_template = {
+ .name = "macsmc-ac",
+ .type = POWER_SUPPLY_TYPE_MAINS,
+ .get_property = macsmc_ac_get_property,
+};
+
+static void macsmc_power_critical_work(struct work_struct *wrk)
+{
+ struct macsmc_power *power = container_of(wrk, struct macsmc_power, critical_work);
+ u16 bitv, b0av;
+ u32 bcf0;
+
+ if (!power->batt)
+ return;
+
+ /*
+ * EMERGENCY: Check voltage vs design minimum.
+ * If we are below BITV, the battery is physically exhausted.
+ * We must shut down NOW to protect the filesystem.
+ */
+ if (apple_smc_read_u16(power->smc, SMC_KEY(BITV), &bitv) >= 0 &&
+ apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &b0av) >= 0 &&
+ b0av < bitv) {
+ dev_crit(power->dev,
+ "Battery voltage (%d mV) below design minimum (%d mV)! Emergency shutdown.\n",
+ b0av, bitv);
+ kernel_power_off();
+ return;
+ }
+
+ /*
+ * Avoid duplicate attempts at orderly shutdown.
+ * Voltage check is above this as we may want to
+ * "upgrade" an orderly shutdown to a critical power
+ * off if voltage drops.
+ */
+ if (power->shutdown_started || system_state > SYSTEM_RUNNING)
+ return;
+
+ /*
+ * Check if SMC flagged the battery as empty.
+ * We trigger a graceful shutdown to let the OS save data.
+ */
+ if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &bcf0) == 0 && bcf0 != 0) {
+ power->shutdown_started = true;
+ dev_emerg(power->dev, "Battery critical (empty flag set). Triggering orderly shutdown.\n");
+ orderly_poweroff(true);
+ }
+}
+
+static int macsmc_power_event(struct notifier_block *nb, unsigned long event, void *data)
+{
+ struct macsmc_power *power = container_of(nb, struct macsmc_power, nb);
+
+ /*
+ * SMC Event IDs are reverse-engineered.
+ * 0x71... indicates power/battery events.
+ */
+ if ((event & 0xffffff00) == 0x71010100 || /* Charger status change */
+ (event & 0xffff0000) == 0x71060000 || /* Port charge state change */
+ (event & 0xffff0000) == 0x71130000) { /* Connector insert/remove event */
+ if (power->batt)
+ power_supply_changed(power->batt);
+ if (power->ac)
+ power_supply_changed(power->ac);
+ return NOTIFY_OK;
+ } else if (event == 0x71020000) {
+ /* Critical battery warning */
+ if (power->batt)
+ schedule_work(&power->critical_work);
+ return NOTIFY_OK;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static int macsmc_power_probe(struct platform_device *pdev)
+{
+ struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
+ struct power_supply_config psy_cfg = {};
+ struct macsmc_power *power;
+ bool has_battery = false;
+ int ret;
+ bool flag;
+ u16 vu16;
+ u32 val32;
+ enum power_supply_property *props;
+ size_t nprops;
+
+ if (!smc)
+ return -ENODEV;
+
+ power = devm_kzalloc(&pdev->dev, sizeof(*power), GFP_KERNEL);
+ if (!power)
+ return -ENOMEM;
+
+ power->dev = &pdev->dev;
+ power->smc = smc;
+ dev_set_drvdata(&pdev->dev, power);
+
+ /*
+ * Check for battery presence.
+ * B0AV is a fundamental key.
+ */
+ if (apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &vu16) == 0 &&
+ macsmc_battery_get_status(power) > POWER_SUPPLY_STATUS_UNKNOWN)
+ has_battery = true;
+
+ if (has_battery) {
+ power->batt_desc = macsmc_battery_desc_template;
+ power->batt_props = devm_kcalloc(&pdev->dev, MACSMC_MAX_BATT_PROPS,
+ sizeof(enum power_supply_property),
+ GFP_KERNEL);
+ if (!power->batt_props)
+ return -ENOMEM;
+
+ props = power->batt_props;
+ nprops = 0;
+
+ /* Fundamental properties */
+ props[nprops++] = POWER_SUPPLY_PROP_STATUS;
+ props[nprops++] = POWER_SUPPLY_PROP_PRESENT;
+ props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_CURRENT_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_POWER_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_CAPACITY;
+ props[nprops++] = POWER_SUPPLY_PROP_CAPACITY_LEVEL;
+ props[nprops++] = POWER_SUPPLY_PROP_TEMP;
+ props[nprops++] = POWER_SUPPLY_PROP_CYCLE_COUNT;
+ props[nprops++] = POWER_SUPPLY_PROP_HEALTH;
+ props[nprops++] = POWER_SUPPLY_PROP_SCOPE;
+ props[nprops++] = POWER_SUPPLY_PROP_MODEL_NAME;
+ props[nprops++] = POWER_SUPPLY_PROP_SERIAL_NUMBER;
+ props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_YEAR;
+ props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_MONTH;
+ props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_DAY;
+
+ /* Extended properties usually present */
+ props[nprops++] = POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_TIME_TO_FULL_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN;
+ props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN;
+ props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MIN;
+ props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MAX;
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT;
+ props[nprops++] = POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX;
+ props[nprops++] = POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE;
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_FULL;
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN;
+ props[nprops++] = POWER_SUPPLY_PROP_ENERGY_FULL;
+ props[nprops++] = POWER_SUPPLY_PROP_ENERGY_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_COUNTER;
+
+ /* Detect features based on key availability */
+ if (apple_smc_key_exists(smc, SMC_KEY(CHTE)))
+ power->has_chte = true;
+ if (apple_smc_key_exists(smc, SMC_KEY(CH0C)))
+ power->has_ch0c = true;
+ if (apple_smc_key_exists(smc, SMC_KEY(CH0I)))
+ power->has_ch0i = true;
+
+ /* Reset "Optimised Battery Charging" flags to default state */
+ if (power->has_chte)
+ apple_smc_write_u32(smc, SMC_KEY(CHTE), 0);
+ else if (power->has_ch0c)
+ apple_smc_write_u8(smc, SMC_KEY(CH0C), 0);
+
+ if (power->has_ch0i)
+ apple_smc_write_u8(smc, SMC_KEY(CH0I), 0);
+
+ apple_smc_write_u8(smc, SMC_KEY(CH0K), 0);
+ apple_smc_write_u8(smc, SMC_KEY(CH0B), 0);
+
+ /* Configure charge behaviour if supported */
+ if (power->has_ch0i || power->has_ch0c || power->has_chte) {
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR;
+
+ power->batt_desc.charge_behaviours =
+ BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO);
+
+ if (power->has_ch0i)
+ power->batt_desc.charge_behaviours |=
+ BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE);
+
+ if (power->has_chte || power->has_ch0c)
+ power->batt_desc.charge_behaviours |=
+ BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE);
+ }
+
+ /* Detect charge limit method (CHWA vs CHLS) */
+ if (apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag) == 0)
+ power->has_chwa = true;
+ else if (apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16) >= 0)
+ power->has_chls = true;
+
+ if (power->has_chwa || power->has_chls) {
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD;
+ props[nprops++] = POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD;
+ }
+
+ power->batt_desc.properties = power->batt_props;
+ power->batt_desc.num_properties = nprops;
+
+ /* Fetch identity strings */
+ apple_smc_read(smc, SMC_KEY(BMDN), power->model_name,
+ sizeof(power->model_name) - 1);
+ apple_smc_read(smc, SMC_KEY(BMSN), power->serial_number,
+ sizeof(power->serial_number) - 1);
+ apple_smc_read(smc, SMC_KEY(BMDT), power->mfg_date,
+ sizeof(power->mfg_date) - 1);
+
+ apple_smc_read_u8(power->smc, SMC_KEY(BNCB), &power->num_cells);
+ power->nominal_voltage_mv = MACSMC_NOMINAL_CELL_VOLTAGE_MV * power->num_cells;
+
+ /* Enable critical shutdown notifications by reading status once */
+ apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val32);
+
+ psy_cfg.drv_data = power;
+ power->batt = devm_power_supply_register(&pdev->dev, &power->batt_desc, &psy_cfg);
+ if (IS_ERR(power->batt)) {
+ ret = dev_err_probe(&pdev->dev, PTR_ERR(power->batt),
+ "Failed to register battery\n");
+ /* Don't return failure yet; try AC registration first */
+ power->batt = NULL;
+ }
+ } else {
+ dev_dbg(&pdev->dev, "No battery detected, proceeding with AC-only registration.\n");
+ }
+
+ /* AC Adapter Registration */
+ power->ac_desc = macsmc_ac_desc_template;
+ power->ac_props = devm_kcalloc(&pdev->dev, MACSMC_MAX_AC_PROPS,
+ sizeof(enum power_supply_property),
+ GFP_KERNEL);
+ if (!power->ac_props)
+ return -ENOMEM;
+
+ props = power->ac_props;
+ nprops = 0;
+
+ /* Online status is fundamental */
+ props[nprops++] = POWER_SUPPLY_PROP_ONLINE;
+
+ /* Input power limits are usually available */
+ if (apple_smc_key_exists(power->smc, SMC_KEY(ACPW)))
+ props[nprops++] = POWER_SUPPLY_PROP_INPUT_POWER_LIMIT;
+
+ /* macOS 15.4+ firmware dropped legacy AC keys (AC-n, AC-i) */
+ if (apple_smc_read_u16(power->smc, SMC_KEY(AC-n), &vu16) >= 0) {
+ props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_NOW;
+ props[nprops++] = POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT;
+ }
+
+ power->ac_desc.properties = power->ac_props;
+ power->ac_desc.num_properties = nprops;
+
+ psy_cfg.drv_data = power;
+ power->ac = devm_power_supply_register(&pdev->dev, &power->ac_desc, &psy_cfg);
+ if (IS_ERR(power->ac)) {
+ ret = dev_err_probe(&pdev->dev, PTR_ERR(power->ac),
+ "Failed to register AC adapter\n");
+ /* If battery also failed or didn't exist, this is a fatal error */
+ if (!power->batt)
+ return ret;
+ power->ac = NULL;
+ }
+
+ /* Final check: did we register anything? */
+ if (!power->batt && !power->ac)
+ return -ENODEV;
+
+ power->nb.notifier_call = macsmc_power_event;
+ blocking_notifier_chain_register(&smc->event_handlers, &power->nb);
+
+ INIT_WORK(&power->critical_work, macsmc_power_critical_work);
+
+ return 0;
+}
+
+static void macsmc_power_remove(struct platform_device *pdev)
+{
+ struct macsmc_power *power = dev_get_drvdata(&pdev->dev);
+
+ blocking_notifier_chain_unregister(&power->smc->event_handlers, &power->nb);
+ cancel_work_sync(&power->critical_work);
+}
+
+static struct platform_driver macsmc_power_driver = {
+ .driver = {
+ .name = "macsmc-power",
+ .owner = THIS_MODULE,
+ },
+ .probe = macsmc_power_probe,
+ .remove = macsmc_power_remove,
+};
+module_platform_driver(macsmc_power_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Apple SMC battery and power management driver");
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_AUTHOR("Michael Reeves <michael.reeves077@gmail.com>");
+MODULE_ALIAS("platform:macsmc-power");
--
2.51.2
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 2/2] mfd: macsmc: Wire up Apple SMC power driver
2026-01-05 12:56 [PATCH 0/2] Add Apple Silicon SMC power driver Michael Reeves via B4 Relay
2026-01-05 12:56 ` [PATCH 1/2] power: supply: Add macsmc-power driver for Apple Silicon Michael Reeves via B4 Relay
@ 2026-01-05 12:56 ` Michael Reeves via B4 Relay
2026-01-07 7:27 ` [PATCH 0/2] Add Apple Silicon " Neal Gompa
2 siblings, 0 replies; 5+ messages in thread
From: Michael Reeves via B4 Relay @ 2026-01-05 12:56 UTC (permalink / raw)
To: Sebastian Reichel, Sven Peter, Janne Grunau, Neal Gompa, Lee Jones
Cc: linux-kernel, linux-pm, asahi, linux-arm-kernel, Michael Reeves,
Hector Martin
From: Michael Reeves <michael.reeves077@gmail.com>
Add the cell for the macsmc-power driver so it is probed by the
MFD core.
Co-developed-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
---
drivers/mfd/macsmc.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/mfd/macsmc.c b/drivers/mfd/macsmc.c
index e3893e255ce5..061b43fc842d 100644
--- a/drivers/mfd/macsmc.c
+++ b/drivers/mfd/macsmc.c
@@ -45,6 +45,7 @@
#define SMC_TIMEOUT_MS 500
static const struct mfd_cell apple_smc_devs[] = {
+ MFD_CELL_NAME("macsmc-power"),
MFD_CELL_OF("macsmc-gpio", NULL, NULL, 0, 0, "apple,smc-gpio"),
MFD_CELL_OF("macsmc-reboot", NULL, NULL, 0, 0, "apple,smc-reboot"),
};
--
2.51.2
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 0/2] Add Apple Silicon SMC power driver
2026-01-05 12:56 [PATCH 0/2] Add Apple Silicon SMC power driver Michael Reeves via B4 Relay
2026-01-05 12:56 ` [PATCH 1/2] power: supply: Add macsmc-power driver for Apple Silicon Michael Reeves via B4 Relay
2026-01-05 12:56 ` [PATCH 2/2] mfd: macsmc: Wire up Apple SMC power driver Michael Reeves via B4 Relay
@ 2026-01-07 7:27 ` Neal Gompa
2 siblings, 0 replies; 5+ messages in thread
From: Neal Gompa @ 2026-01-07 7:27 UTC (permalink / raw)
To: michael.reeves077
Cc: Sebastian Reichel, Sven Peter, Janne Grunau, Lee Jones,
linux-kernel, linux-pm, asahi, linux-arm-kernel, Hector Martin
On Mon, Jan 5, 2026 at 7:56 AM Michael Reeves via B4 Relay
<devnull+michael.reeves077.gmail.com@kernel.org> wrote:
>
> This series adds a power supply driver for the Apple SMC found on
> Apple Silicon devices. This allows the kernel to report AC status,
> battery charging status, and power metrics, and modify the charging
> behaviour.
>
> The first patch adds the driver itself, and the second patch wires it
> up to the MFD core.
>
> The driver is based on an original out-of-tree implementation by
> Hector Martin. It has been refactored for upstream inclusion,
> including support for newer SMC firmwares, devices without batteries,
> dynamic property detection and improved state management.
>
> Tested on: Apple M3 (MacBook Air, J613)
>
> Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
> ---
> Michael Reeves (2):
> power: supply: Add macsmc-power driver for Apple Silicon
> mfd: macsmc: Wire up Apple SMC power driver
>
> MAINTAINERS | 1 +
> drivers/mfd/macsmc.c | 1 +
> drivers/power/supply/Kconfig | 11 +
> drivers/power/supply/Makefile | 1 +
> drivers/power/supply/macsmc-power.c | 872 ++++++++++++++++++++++++++++++++++++
> 5 files changed, 886 insertions(+)
> ---
> base-commit: cc3aa43b44bdb43dfbac0fcb51c56594a11338a8
> change-id: 20260105-b4-macsmc-power-d017cc7f53ac
>
LGTM, thanks for this work!
Reviewed-by: Neal Gompa <neal@gompa.dev>
--
真実はいつも一つ！/ Always, there's only one truth!
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] power: supply: Add macsmc-power driver for Apple Silicon
2026-01-05 12:56 ` [PATCH 1/2] power: supply: Add macsmc-power driver for Apple Silicon Michael Reeves via B4 Relay
@ 2026-01-07 14:35 ` Nick Chan
0 siblings, 0 replies; 5+ messages in thread
From: Nick Chan @ 2026-01-07 14:35 UTC (permalink / raw)
To: michael.reeves077, Sebastian Reichel, Sven Peter, Janne Grunau,
Neal Gompa, Lee Jones
Cc: linux-kernel, linux-pm, asahi, linux-arm-kernel, Hector Martin
On 5/1/2026 20:56, Michael Reeves via B4 Relay wrote:
> From: Michael Reeves <michael.reeves077@gmail.com>
>
> This driver provides battery and AC status monitoring for Apple Silicon
> Macs via the SMC (System Management Controller). It supports
> reporting capacity, voltage, current, and charging status.
>
> Co-developed-by: Hector Martin <marcan@marcan.st>
> Signed-off-by: Hector Martin <marcan@marcan.st>
> Signed-off-by: Michael Reeves <michael.reeves077@gmail.com>
> ---
> MAINTAINERS | 1 +
> drivers/power/supply/Kconfig | 11 +
> drivers/power/supply/Makefile | 1 +
> drivers/power/supply/macsmc-power.c | 872 ++++++++++++++++++++++++++++++++++++
> 4 files changed, 885 insertions(+)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0dbf349fc1ed..c18da2295477 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2507,6 +2507,7 @@ F: drivers/nvmem/apple-efuses.c
> F: drivers/nvmem/apple-spmi-nvmem.c
> F: drivers/pinctrl/pinctrl-apple-gpio.c
> F: drivers/power/reset/macsmc-reboot.c
> +F: drivers/power/supply/macsmc-power.c
> F: drivers/pwm/pwm-apple.c
> F: drivers/rtc/rtc-macsmc.c
> F: drivers/soc/apple/*
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index 92f9f7aae92f..3a5b7d9234c2 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -1132,4 +1132,15 @@ config FUEL_GAUGE_MM8013
> the state of charge, temperature, cycle count, actual and design
> capacity, etc.
>
> +config MACSMC_POWER
> + tristate "Apple SMC Battery and Power Driver"
> + depends on MFD_MACSMC
> + help
> + This driver provides support for the battery and AC adapter on
> + Apple Silicon machines. It exposes battery telemetry (voltage,
> + current, health) and AC adapter status through the standard Linux
> + power supply framework.
> +
> + Say Y or M here if you have an Apple Silicon based Mac.
> +
> endif # POWER_SUPPLY
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index 4b79d5abc49a..f5333096f0c3 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -128,3 +128,4 @@ obj-$(CONFIG_CHARGER_SURFACE) += surface_charger.o
> obj-$(CONFIG_BATTERY_UG3105) += ug3105_battery.o
> obj-$(CONFIG_CHARGER_QCOM_SMB2) += qcom_smbx.o
> obj-$(CONFIG_FUEL_GAUGE_MM8013) += mm8013.o
> +obj-$(CONFIG_MACSMC_POWER) += macsmc-power.o
Please use a tab here so the object filenames are aligned.
> diff --git a/drivers/power/supply/macsmc-power.c b/drivers/power/supply/macsmc-power.c
> new file mode 100644
> index 000000000000..def9b12118c2
> --- /dev/null
> +++ b/drivers/power/supply/macsmc-power.c
> @@ -0,0 +1,872 @@
> +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> +/*
> + * Apple SMC Power/Battery Management Driver
> + *
> + * This driver exposes battery telemetry (voltage, current, temperature, health)
> + * and AC adapter status provided by the Apple SMC (System Management Controller)
> + * on Apple Silicon systems.
> + *
> + * Copyright The Asahi Linux Contributors
> + */
> +
> +#include <linux/ctype.h>
> +#include <linux/delay.h>
> +#include <linux/limits.h>
> +#include <linux/module.h>
> +#include <linux/mfd/macsmc.h>
> +#include <linux/notifier.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/reboot.h>
> +#include <linux/workqueue.h>
> +
> +#define MAX_STRING_LENGTH 256
> +
> +/*
> + * The SMC reports charge in mAh (Coulombs) but energy in mWh (Joules).
> + * We lack a register for "Nominal Voltage" or "Energy Accumulator".
> + * We use a fixed 3.8V/cell constant to approximate energy stats for userspace,
> + * derived from empirical data across supported MacBook models.
> + */
> +#define MACSMC_NOMINAL_CELL_VOLTAGE_MV 3800
> +
> +/* SMC Key Flags */
> +#define CHNC_BATTERY_FULL BIT(0)
> +#define CHNC_NO_CHARGER BIT(7)
> +#define CHNC_NOCHG_CH0C BIT(14)
> +#define CHNC_NOCHG_CH0B_CH0K BIT(15)
> +#define CHNC_BATTERY_FULL_2 BIT(18)
> +#define CHNC_BMS_BUSY BIT(23)
> +#define CHNC_CHLS_LIMIT BIT(24)
> +#define CHNC_NOAC_CH0J BIT(53)
> +#define CHNC_NOAC_CH0I BIT(54)
> +
> +#define CH0R_LOWER_FLAGS GENMASK(15, 0)
> +#define CH0R_NOAC_CH0I BIT(0)
> +#define CH0R_NOAC_DISCONNECTED BIT(4)
> +#define CH0R_NOAC_CH0J BIT(5)
> +#define CH0R_BMS_BUSY BIT(8)
> +#define CH0R_NOAC_CH0K BIT(9)
> +#define CH0R_NOAC_CHWA BIT(11)
> +
> +#define CH0X_CH0C BIT(0)
> +#define CH0X_CH0B BIT(1)
> +
> +#define ACSt_CAN_BOOT_AP BIT(2)
> +#define ACSt_CAN_BOOT_IBOOT BIT(1)
> +
> +#define CHWA_CHLS_FIXED_START_OFFSET 5
> +#define CHLS_MIN_END_THRESHOLD 10
> +#define CHLS_FORCE_DISCHARGE 0x100
> +#define CHWA_FIXED_END_THRESHOLD 80
> +#define CHWA_PROP_WRITE_THRESHOLD 95
> +
> +#define MACSMC_MAX_BATT_PROPS 50
> +#define MACSMC_MAX_AC_PROPS 10
> +
> +struct macsmc_power {
> + struct device *dev;
> + struct apple_smc *smc;
> +
> + struct power_supply_desc ac_desc;
> + struct power_supply_desc batt_desc;
> +
> + enum power_supply_property *ac_props;
> + enum power_supply_property *batt_props;
> +
> + struct power_supply *batt;
> + struct power_supply *ac;
> +
> + char model_name[MAX_STRING_LENGTH];
> + char serial_number[MAX_STRING_LENGTH];
> + char mfg_date[MAX_STRING_LENGTH];
> +
> + bool has_chwa;
> + bool has_chls;
> + bool has_ch0i;
> + bool has_ch0c;
> + bool has_chte;
> +
> + u8 num_cells;
> + int nominal_voltage_mv;
> +
> + struct notifier_block nb;
> + struct work_struct critical_work;
> + bool shutdown_started;
> +};
> +
> +static int macsmc_battery_get_status(struct macsmc_power *power)
> +{
> + u64 nocharge_flags;
> + u32 nopower_flags;
> + u16 ac_current;
> + int charge_limit = 0;
> + bool limited = false;
> + bool flag;
> + int ret;
> +
> + /*
> + * Fallbacks exist for keys that may disappear in future hardware.
> + * CHCE/CHCC/BSFC/CHSC are considered fundamental; absence is an error.
> + */
> +
> + /* Check if power input is inhibited (e.g. BMS balancing cycle) */
> + ret = apple_smc_read_u32(power->smc, SMC_KEY(CH0R), &nopower_flags);
> + if (!ret && (nopower_flags & CH0R_LOWER_FLAGS & ~CH0R_BMS_BUSY))
> + return POWER_SUPPLY_STATUS_DISCHARGING;
> +
> + /* Check if charger is present */
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(CHCE), &flag);
> + if (ret < 0)
> + return ret;
> + if (!flag)
> + return POWER_SUPPLY_STATUS_DISCHARGING;
> +
> + /* Check if AC is charge capable */
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(CHCC), &flag);
> + if (ret < 0)
> + return ret;
> + if (!flag)
> + return POWER_SUPPLY_STATUS_DISCHARGING;
> +
> + /* Check if AC input limit is too low */
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-i), &ac_current);
> + if (!ret && ac_current < 100)
> + return POWER_SUPPLY_STATUS_DISCHARGING;
> +
> + /* Check if battery is full */
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(BSFC), &flag);
> + if (ret < 0)
> + return ret;
> + if (flag)
> + return POWER_SUPPLY_STATUS_FULL;
> +
> + /* Check for user-defined charge limits */
> + if (power->has_chls) {
> + u16 vu16;
> +
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16);
> + if (ret == 0 && (vu16 & 0xff) >= CHLS_MIN_END_THRESHOLD)
> + charge_limit = (vu16 & 0xff) - CHWA_CHLS_FIXED_START_OFFSET;
> + } else if (power->has_chwa) {
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag);
> + if (ret == 0 && flag)
> + charge_limit = CHWA_FIXED_END_THRESHOLD - CHWA_CHLS_FIXED_START_OFFSET;
> + }
> +
> + if (charge_limit > 0) {
> + u8 buic = 0;
> +
> + if (apple_smc_read_u8(power->smc, SMC_KEY(BUIC), &buic) >= 0 &&
> + buic >= charge_limit)
> + limited = true;
> + }
> +
> + /* Check charging inhibitors */
> + ret = apple_smc_read_u64(power->smc, SMC_KEY(CHNC), &nocharge_flags);
> + if (!ret) {
> + if (nocharge_flags & CHNC_BATTERY_FULL)
> + return POWER_SUPPLY_STATUS_FULL;
> + /* BMS busy shows up as inhibit, but we treat it as charging */
> + else if (nocharge_flags == CHNC_BMS_BUSY && !limited)
> + return POWER_SUPPLY_STATUS_CHARGING;
> + else if (nocharge_flags)
> + return POWER_SUPPLY_STATUS_NOT_CHARGING;
> + else
> + return POWER_SUPPLY_STATUS_CHARGING;
> + }
> +
> + /* Fallback: System charging flag */
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(CHSC), &flag);
> + if (ret < 0)
> + return ret;
> + if (!flag)
> + return POWER_SUPPLY_STATUS_NOT_CHARGING;
> +
> + return POWER_SUPPLY_STATUS_CHARGING;
> +}
> +
> +static int macsmc_battery_get_charge_behaviour(struct macsmc_power *power)
> +{
> + int ret;
> + u8 val8;
> + u8 chte_buf[4];
> +
> + if (power->has_ch0i) {
> + ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0I), &val8);
> + if (ret)
> + return ret;
> + if (val8 & CH0R_NOAC_CH0I)
> + return POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE;
> + }
> +
> + if (power->has_chte) {
> + ret = apple_smc_read(power->smc, SMC_KEY(CHTE), chte_buf, 4);
> + if (ret < 0)
> + return ret;
> +
> + if (chte_buf[0] == 0x01)
> + return POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
> + } else if (power->has_ch0c) {
> + ret = apple_smc_read_u8(power->smc, SMC_KEY(CH0C), &val8);
> + if (ret)
> + return ret;
> + if (val8 & CH0X_CH0C)
> + return POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE;
> + }
> +
> + return POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO;
> +}
> +
> +static int macsmc_battery_set_charge_behaviour(struct macsmc_power *power, int val)
> +{
> + int ret;
> +
> + /* First, reset all inhibitors to a known-good 'auto' state */
> + if (power->has_ch0i) {
> + ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 0);
> + if (ret)
> + return ret;
> + }
> +
> + if (power->has_chte) {
> + ret = apple_smc_write_u32(power->smc, SMC_KEY(CHTE), 0);
> + if (ret)
> + return ret;
> + } else if (power->has_ch0c) {
> + ret = apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 0);
> + if (ret)
> + return ret;
> + }
> +
> + switch (val) {
> + case POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO:
> + return 0;
> +
> + case POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE:
> + if (power->has_chte)
> + return apple_smc_write_u32(power->smc, SMC_KEY(CHTE), 1);
> + else if (power->has_ch0c)
> + return apple_smc_write_u8(power->smc, SMC_KEY(CH0C), 1);
> + else
> + return -EOPNOTSUPP;
> + break;
> +
> + case POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE:
> + if (!power->has_ch0i)
> + return -EOPNOTSUPP;
> + return apple_smc_write_u8(power->smc, SMC_KEY(CH0I), 1);
> +
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int macsmc_battery_get_date(const char *s, int *out)
> +{
> + if (!isdigit(s[0]) || !isdigit(s[1]))
> + return -EOPNOTSUPP;
> +
> + *out = (s[0] - '0') * 10 + s[1] - '0';
> + return 0;
> +}
> +
> +static int macsmc_battery_get_capacity_level(struct macsmc_power *power)
> +{
> + bool flag;
> + u32 val;
> + int ret;
> +
> + /* Check for emergency shutdown condition */
> + if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val) >= 0 && val)
> + return POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
> +
> + /* Check AC status for whether we could boot in this state */
> + if (apple_smc_read_u32(power->smc, SMC_KEY(ACSt), &val) >= 0) {
> + if (!(val & ACSt_CAN_BOOT_IBOOT))
> + return POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
> +
> + if (!(val & ACSt_CAN_BOOT_AP))
> + return POWER_SUPPLY_CAPACITY_LEVEL_LOW;
> + }
> +
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(BSFC), &flag);
> + if (ret < 0)
> + return POWER_SUPPLY_CAPACITY_LEVEL_UNKNOWN;
> +
> + if (flag)
> + return POWER_SUPPLY_CAPACITY_LEVEL_FULL;
> + else
> + return POWER_SUPPLY_CAPACITY_LEVEL_NORMAL;
> +}
> +
> +static int macsmc_battery_get_property(struct power_supply *psy,
> + enum power_supply_property psp,
> + union power_supply_propval *val)
> +{
> + struct macsmc_power *power = power_supply_get_drvdata(psy);
> + int ret = 0;
> + u8 vu8;
> + u16 vu16;
> + s16 vs16;
> + s32 vs32;
> + s64 vs64;
> + bool flag;
> +
> + switch (psp) {
> + case POWER_SUPPLY_PROP_STATUS:
> + val->intval = macsmc_battery_get_status(power);
> + ret = val->intval < 0 ? val->intval : 0;
> + break;
> + case POWER_SUPPLY_PROP_PRESENT:
> + val->intval = 1;
> + break;
> + case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
> + val->intval = macsmc_battery_get_charge_behaviour(power);
> + ret = val->intval < 0 ? val->intval : 0;
> + break;
> + case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0TE), &vu16);
> + val->intval = vu16 == 0xffff ? 0 : vu16 * 60;
> + break;
> + case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0TF), &vu16);
> + val->intval = vu16 == 0xffff ? 0 : vu16 * 60;
> + break;
> + case POWER_SUPPLY_PROP_CAPACITY:
> + ret = apple_smc_read_u8(power->smc, SMC_KEY(BUIC), &vu8);
> + val->intval = vu8;
> + break;
> + case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
> + val->intval = macsmc_battery_get_capacity_level(power);
> + ret = val->intval < 0 ? val->intval : 0;
> + break;
> + case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_CURRENT_NOW:
> + ret = apple_smc_read_s16(power->smc, SMC_KEY(B0AC), &vs16);
> + val->intval = vs16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_POWER_NOW:
> + ret = apple_smc_read_s32(power->smc, SMC_KEY(B0AP), &vs32);
> + val->intval = vs32 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(BITV), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
> + /* Calculate total max design voltage from per-cell nominal voltage */
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(BVVN), &vu16);
> + val->intval = vu16 * 1000 * power->num_cells;
> + break;
> + case POWER_SUPPLY_PROP_VOLTAGE_MIN:
> + /* Lifetime min */
> + ret = apple_smc_read_s16(power->smc, SMC_KEY(BLPM), &vs16);
> + val->intval = vs16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_VOLTAGE_MAX:
> + /* Lifetime max */
> + ret = apple_smc_read_s16(power->smc, SMC_KEY(BLPX), &vs16);
> + val->intval = vs16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RC), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RI), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RV), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0DC), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_CHARGE_FULL:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0FC), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_CHARGE_NOW:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
> + /* B0RM is Big Endian, likely pass through from TI gas gauge */
> + val->intval = (s16)swab16(vu16) * 1000;
> + break;
> + case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0DC), &vu16);
> + val->intval = vu16 * power->nominal_voltage_mv;
> + break;
> + case POWER_SUPPLY_PROP_ENERGY_FULL:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0FC), &vu16);
> + val->intval = vu16 * power->nominal_voltage_mv;
> + break;
> + case POWER_SUPPLY_PROP_ENERGY_NOW:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
> + /* B0RM is Big Endian, likely pass through from TI gas gauge */
> + val->intval = (s16)swab16(vu16) * power->nominal_voltage_mv;
> + break;
> + case POWER_SUPPLY_PROP_TEMP:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0AT), &vu16);
> + val->intval = vu16 - 2732; /* Kelvin x10 to Celsius x10 */
> + break;
> + case POWER_SUPPLY_PROP_CHARGE_COUNTER:
> + ret = apple_smc_read_s64(power->smc, SMC_KEY(BAAC), &vs64);
> + val->intval = vs64;
> + break;
> + case POWER_SUPPLY_PROP_CYCLE_COUNT:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(B0CT), &vu16);
> + val->intval = vu16;
> + break;
> + case POWER_SUPPLY_PROP_SCOPE:
> + val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
> + break;
> + case POWER_SUPPLY_PROP_HEALTH:
> + flag = false;
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(BBAD), &flag);
> + val->intval = flag ? POWER_SUPPLY_HEALTH_DEAD : POWER_SUPPLY_HEALTH_GOOD;
> + break;
> + case POWER_SUPPLY_PROP_MODEL_NAME:
> + val->strval = power->model_name;
> + break;
> + case POWER_SUPPLY_PROP_SERIAL_NUMBER:
> + val->strval = power->serial_number;
> + break;
> + case POWER_SUPPLY_PROP_MANUFACTURE_YEAR:
> + ret = macsmc_battery_get_date(&power->mfg_date[0], &val->intval);
> + /* The SMC reports the manufacture year as an offset from 1992. */
> + val->intval += 1992;
> + break;
> + case POWER_SUPPLY_PROP_MANUFACTURE_MONTH:
> + ret = macsmc_battery_get_date(&power->mfg_date[2], &val->intval);
> + break;
> + case POWER_SUPPLY_PROP_MANUFACTURE_DAY:
> + ret = macsmc_battery_get_date(&power->mfg_date[4], &val->intval);
> + break;
> + case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
> + case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
> + if (power->has_chls) {
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16);
> + val->intval = vu16 & 0xff;
> + if (val->intval < CHLS_MIN_END_THRESHOLD || val->intval >= 100)
> + val->intval = 100;
> + } else if (power->has_chwa) {
> + flag = false;
> + ret = apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag);
> + val->intval = flag ? CHWA_FIXED_END_THRESHOLD : 100;
> + } else {
> + return -EINVAL;
> + }
> + if (psp == POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD &&
> + ret >= 0 && val->intval < 100 && val->intval >= CHLS_MIN_END_THRESHOLD)
> + val->intval -= CHWA_CHLS_FIXED_START_OFFSET;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return ret;
> +}
> +
> +static int macsmc_battery_set_property(struct power_supply *psy,
> + enum power_supply_property psp,
> + const union power_supply_propval *val)
> +{
> + struct macsmc_power *power = power_supply_get_drvdata(psy);
> +
> + switch (psp) {
> + case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
> + return macsmc_battery_set_charge_behaviour(power, val->intval);
> + case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
> + /*
> + * Read-only reflection of end threshold logic.
> + * Allowed to be written to avoid userspace confusion, but ignored.
> + */
> + return 0;
> + case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
> + if (power->has_chls) {
> + u16 kval = 0;
> + /* Configurable logic for future expansion */
> + if (val->intval < CHLS_MIN_END_THRESHOLD)
> + kval = CHLS_FORCE_DISCHARGE | CHLS_MIN_END_THRESHOLD;
> + else if (val->intval < 100)
> + kval = CHLS_FORCE_DISCHARGE | (val->intval & 0xff);
> +
> + return apple_smc_write_u16(power->smc, SMC_KEY(CHLS), kval);
> + } else if (power->has_chwa) {
> + return apple_smc_write_flag(power->smc, SMC_KEY(CHWA),
> + val->intval <= CHWA_PROP_WRITE_THRESHOLD);
> + } else {
> + return -EINVAL;
> + }
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int macsmc_battery_property_is_writeable(struct power_supply *psy,
> + enum power_supply_property psp)
> +{
> + struct macsmc_power *power = power_supply_get_drvdata(psy);
> +
> + switch (psp) {
> + case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
> + return true;
> + case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
> + case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
> + return power->has_chwa || power->has_chls;
> + default:
> + return false;
> + }
> +}
> +
> +static const struct power_supply_desc macsmc_battery_desc_template = {
> + .name = "macsmc-battery",
> + .type = POWER_SUPPLY_TYPE_BATTERY,
> + .get_property = macsmc_battery_get_property,
> + .set_property = macsmc_battery_set_property,
> + .property_is_writeable = macsmc_battery_property_is_writeable,
> +};
> +
> +static int macsmc_ac_get_property(struct power_supply *psy,
> + enum power_supply_property psp,
> + union power_supply_propval *val)
> +{
> + struct macsmc_power *power = power_supply_get_drvdata(psy);
> + int ret = 0;
> + u16 vu16;
> + u32 vu32;
> +
> + switch (psp) {
> + case POWER_SUPPLY_PROP_ONLINE:
> + ret = apple_smc_read_u32(power->smc, SMC_KEY(CHIS), &vu32);
> + val->intval = !!vu32;
> + break;
> + case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-n), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> + ret = apple_smc_read_u16(power->smc, SMC_KEY(AC-i), &vu16);
> + val->intval = vu16 * 1000;
> + break;
> + case POWER_SUPPLY_PROP_INPUT_POWER_LIMIT:
> + ret = apple_smc_read_u32(power->smc, SMC_KEY(ACPW), &vu32);
> + val->intval = vu32 * 1000;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return ret;
> +}
> +
> +static const struct power_supply_desc macsmc_ac_desc_template = {
> + .name = "macsmc-ac",
> + .type = POWER_SUPPLY_TYPE_MAINS,
> + .get_property = macsmc_ac_get_property,
> +};
> +
> +static void macsmc_power_critical_work(struct work_struct *wrk)
> +{
> + struct macsmc_power *power = container_of(wrk, struct macsmc_power, critical_work);
> + u16 bitv, b0av;
> + u32 bcf0;
> +
> + if (!power->batt)
> + return;
> +
> + /*
> + * EMERGENCY: Check voltage vs design minimum.
> + * If we are below BITV, the battery is physically exhausted.
> + * We must shut down NOW to protect the filesystem.
> + */
> + if (apple_smc_read_u16(power->smc, SMC_KEY(BITV), &bitv) >= 0 &&
> + apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &b0av) >= 0 &&
> + b0av < bitv) {
> + dev_crit(power->dev,
> + "Battery voltage (%d mV) below design minimum (%d mV)! Emergency shutdown.\n",
> + b0av, bitv);
This log should probably be dev_emerg(...); More so than the orderly
poweroff below.
> + kernel_power_off();
> + return;
> + }
> +
> + /*
> + * Avoid duplicate attempts at orderly shutdown.
> + * Voltage check is above this as we may want to
> + * "upgrade" an orderly shutdown to a critical power
> + * off if voltage drops.
> + */
> + if (power->shutdown_started || system_state > SYSTEM_RUNNING)
> + return;
> +
> + /*
> + * Check if SMC flagged the battery as empty.
> + * We trigger a graceful shutdown to let the OS save data.
> + */
> + if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &bcf0) == 0 && bcf0 != 0) {
> + power->shutdown_started = true;
> + dev_emerg(power->dev, "Battery critical (empty flag set). Triggering orderly shutdown.\n");
> + orderly_poweroff(true);
> + }
> +}
> +
> +static int macsmc_power_event(struct notifier_block *nb, unsigned long event, void *data)
> +{
> + struct macsmc_power *power = container_of(nb, struct macsmc_power, nb);
> +
> + /*
> + * SMC Event IDs are reverse-engineered.
> + * 0x71... indicates power/battery events.
> + */
> + if ((event & 0xffffff00) == 0x71010100 || /* Charger status change */
> + (event & 0xffff0000) == 0x71060000 || /* Port charge state change */
> + (event & 0xffff0000) == 0x71130000) { /* Connector insert/remove event */
> + if (power->batt)
> + power_supply_changed(power->batt);
> + if (power->ac)
> + power_supply_changed(power->ac);
> + return NOTIFY_OK;
> + } else if (event == 0x71020000) {
> + /* Critical battery warning */
> + if (power->batt)
> + schedule_work(&power->critical_work);
> + return NOTIFY_OK;
> + }
> +
> + return NOTIFY_DONE;
> +}
> +
> +static int macsmc_power_probe(struct platform_device *pdev)
> +{
> + struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
> + struct power_supply_config psy_cfg = {};
> + struct macsmc_power *power;
> + bool has_battery = false;
> + int ret;
> + bool flag;
> + u16 vu16;
> + u32 val32;
> + enum power_supply_property *props;
> + size_t nprops;
> +
> + if (!smc)
> + return -ENODEV;
> +
> + power = devm_kzalloc(&pdev->dev, sizeof(*power), GFP_KERNEL);
> + if (!power)
> + return -ENOMEM;
> +
> + power->dev = &pdev->dev;
> + power->smc = smc;
> + dev_set_drvdata(&pdev->dev, power);
> +
> + /*
> + * Check for battery presence.
> + * B0AV is a fundamental key.
> + */
> + if (apple_smc_read_u16(power->smc, SMC_KEY(B0AV), &vu16) == 0 &&
> + macsmc_battery_get_status(power) > POWER_SUPPLY_STATUS_UNKNOWN)
> + has_battery = true;
> +
> + if (has_battery) {
> + power->batt_desc = macsmc_battery_desc_template;
> + power->batt_props = devm_kcalloc(&pdev->dev, MACSMC_MAX_BATT_PROPS,
> + sizeof(enum power_supply_property),
> + GFP_KERNEL);
> + if (!power->batt_props)
> + return -ENOMEM;
> +
> + props = power->batt_props;
> + nprops = 0;
> +
> + /* Fundamental properties */
> + props[nprops++] = POWER_SUPPLY_PROP_STATUS;
> + props[nprops++] = POWER_SUPPLY_PROP_PRESENT;
> + props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_CURRENT_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_POWER_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_CAPACITY;
> + props[nprops++] = POWER_SUPPLY_PROP_CAPACITY_LEVEL;
> + props[nprops++] = POWER_SUPPLY_PROP_TEMP;
> + props[nprops++] = POWER_SUPPLY_PROP_CYCLE_COUNT;
> + props[nprops++] = POWER_SUPPLY_PROP_HEALTH;
> + props[nprops++] = POWER_SUPPLY_PROP_SCOPE;
> + props[nprops++] = POWER_SUPPLY_PROP_MODEL_NAME;
> + props[nprops++] = POWER_SUPPLY_PROP_SERIAL_NUMBER;
> + props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_YEAR;
> + props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_MONTH;
> + props[nprops++] = POWER_SUPPLY_PROP_MANUFACTURE_DAY;
> +
> + /* Extended properties usually present */
> + props[nprops++] = POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_TIME_TO_FULL_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN;
> + props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN;
> + props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MIN;
> + props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_MAX;
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT;
> + props[nprops++] = POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX;
> + props[nprops++] = POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE;
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_FULL;
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN;
> + props[nprops++] = POWER_SUPPLY_PROP_ENERGY_FULL;
> + props[nprops++] = POWER_SUPPLY_PROP_ENERGY_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_COUNTER;
> +
> + /* Detect features based on key availability */
> + if (apple_smc_key_exists(smc, SMC_KEY(CHTE)))
> + power->has_chte = true;
> + if (apple_smc_key_exists(smc, SMC_KEY(CH0C)))
> + power->has_ch0c = true;
> + if (apple_smc_key_exists(smc, SMC_KEY(CH0I)))
> + power->has_ch0i = true;
> +
> + /* Reset "Optimised Battery Charging" flags to default state */
> + if (power->has_chte)
> + apple_smc_write_u32(smc, SMC_KEY(CHTE), 0);
> + else if (power->has_ch0c)
> + apple_smc_write_u8(smc, SMC_KEY(CH0C), 0);
> +
> + if (power->has_ch0i)
> + apple_smc_write_u8(smc, SMC_KEY(CH0I), 0);
> +
> + apple_smc_write_u8(smc, SMC_KEY(CH0K), 0);
> + apple_smc_write_u8(smc, SMC_KEY(CH0B), 0);
> +
> + /* Configure charge behaviour if supported */
> + if (power->has_ch0i || power->has_ch0c || power->has_chte) {
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR;
> +
> + power->batt_desc.charge_behaviours =
> + BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_AUTO);
> +
> + if (power->has_ch0i)
> + power->batt_desc.charge_behaviours |=
> + BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_FORCE_DISCHARGE);
> +
> + if (power->has_chte || power->has_ch0c)
> + power->batt_desc.charge_behaviours |=
> + BIT(POWER_SUPPLY_CHARGE_BEHAVIOUR_INHIBIT_CHARGE);
> + }
> +
> + /* Detect charge limit method (CHWA vs CHLS) */
> + if (apple_smc_read_flag(power->smc, SMC_KEY(CHWA), &flag) == 0)
> + power->has_chwa = true;
> + else if (apple_smc_read_u16(power->smc, SMC_KEY(CHLS), &vu16) >= 0)
> + power->has_chls = true;
> +
> + if (power->has_chwa || power->has_chls) {
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD;
> + props[nprops++] = POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD;
> + }
> +
> + power->batt_desc.properties = power->batt_props;
> + power->batt_desc.num_properties = nprops;
> +
> + /* Fetch identity strings */
> + apple_smc_read(smc, SMC_KEY(BMDN), power->model_name,
> + sizeof(power->model_name) - 1);
> + apple_smc_read(smc, SMC_KEY(BMSN), power->serial_number,
> + sizeof(power->serial_number) - 1);
> + apple_smc_read(smc, SMC_KEY(BMDT), power->mfg_date,
> + sizeof(power->mfg_date) - 1);
> +
> + apple_smc_read_u8(power->smc, SMC_KEY(BNCB), &power->num_cells);
> + power->nominal_voltage_mv = MACSMC_NOMINAL_CELL_VOLTAGE_MV * power->num_cells;
> +
> + /* Enable critical shutdown notifications by reading status once */
> + apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val32);
> +
> + psy_cfg.drv_data = power;
> + power->batt = devm_power_supply_register(&pdev->dev, &power->batt_desc, &psy_cfg);
> + if (IS_ERR(power->batt)) {
> + ret = dev_err_probe(&pdev->dev, PTR_ERR(power->batt),
> + "Failed to register battery\n");
> + /* Don't return failure yet; try AC registration first */
> + power->batt = NULL;
> + }
> + } else {
> + dev_dbg(&pdev->dev, "No battery detected, proceeding with AC-only registration.\n");
> + }
Desktop devices won't have AC properties either. Check the CHIS key before
attempting to register the AC adapter.
> +
> + /* AC Adapter Registration */
> + power->ac_desc = macsmc_ac_desc_template;
> + power->ac_props = devm_kcalloc(&pdev->dev, MACSMC_MAX_AC_PROPS,
> + sizeof(enum power_supply_property),
> + GFP_KERNEL);
> + if (!power->ac_props)
> + return -ENOMEM;
> +
> + props = power->ac_props;
> + nprops = 0;
> +
> + /* Online status is fundamental */
> + props[nprops++] = POWER_SUPPLY_PROP_ONLINE;
> +
> + /* Input power limits are usually available */
> + if (apple_smc_key_exists(power->smc, SMC_KEY(ACPW)))
> + props[nprops++] = POWER_SUPPLY_PROP_INPUT_POWER_LIMIT;
> +
> + /* macOS 15.4+ firmware dropped legacy AC keys (AC-n, AC-i) */
> + if (apple_smc_read_u16(power->smc, SMC_KEY(AC-n), &vu16) >= 0) {
> + props[nprops++] = POWER_SUPPLY_PROP_VOLTAGE_NOW;
> + props[nprops++] = POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT;
> + }
> +
> + power->ac_desc.properties = power->ac_props;
> + power->ac_desc.num_properties = nprops;
> +
> + psy_cfg.drv_data = power;
> + power->ac = devm_power_supply_register(&pdev->dev, &power->ac_desc, &psy_cfg);
> + if (IS_ERR(power->ac)) {
> + ret = dev_err_probe(&pdev->dev, PTR_ERR(power->ac),
> + "Failed to register AC adapter\n");
> + /* If battery also failed or didn't exist, this is a fatal error */
> + if (!power->batt)
> + return ret;
> + power->ac = NULL;
> + }
> +
> + /* Final check: did we register anything? */
> + if (!power->batt && !power->ac)
> + return -ENODEV;
> +
> + power->nb.notifier_call = macsmc_power_event;
> + blocking_notifier_chain_register(&smc->event_handlers, &power->nb);
> +
> + INIT_WORK(&power->critical_work, macsmc_power_critical_work);
> +
> + return 0;
> +}
> +
> +static void macsmc_power_remove(struct platform_device *pdev)
> +{
> + struct macsmc_power *power = dev_get_drvdata(&pdev->dev);
> +
> + blocking_notifier_chain_unregister(&power->smc->event_handlers, &power->nb);
> + cancel_work_sync(&power->critical_work);
> +}
> +
> +static struct platform_driver macsmc_power_driver = {
> + .driver = {
> + .name = "macsmc-power",
> + .owner = THIS_MODULE,
> + },
> + .probe = macsmc_power_probe,
> + .remove = macsmc_power_remove,
> +};
> +module_platform_driver(macsmc_power_driver);
> +
> +MODULE_LICENSE("Dual MIT/GPL");
> +MODULE_DESCRIPTION("Apple SMC battery and power management driver");
> +MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
> +MODULE_AUTHOR("Michael Reeves <michael.reeves077@gmail.com>");
> +MODULE_ALIAS("platform:macsmc-power");
>
Best regards,
Nick Chan
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2026-01-07 14:35 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-01-05 12:56 [PATCH 0/2] Add Apple Silicon SMC power driver Michael Reeves via B4 Relay
2026-01-05 12:56 ` [PATCH 1/2] power: supply: Add macsmc-power driver for Apple Silicon Michael Reeves via B4 Relay
2026-01-07 14:35 ` Nick Chan
2026-01-05 12:56 ` [PATCH 2/2] mfd: macsmc: Wire up Apple SMC power driver Michael Reeves via B4 Relay
2026-01-07 7:27 ` [PATCH 0/2] Add Apple Silicon " Neal Gompa
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